Welding is one of the usual assembling methods with various applications. Thedifferent defects are generated during welding and also in service conditions. After inspection andidentifying the defects, the repairs are applied. Welding repair operation causes the mechanicalproperties and the microstructures of weldment to change. In the present work the variations ofyield stress, hardness and microstructures in the A 36 repair butt specimens were investigated bythe experimental study. The welding technique was Tungsten Insert Gas method without usingfiller. The specimens were cut from the welded plates using water jet method for avoiding heateffect during the cutting. The low-carbon steel A 36 thin plate was used to construct thespecimens. This material has numerous applications to construct various structures and parts. Thespecifications of specimens and tests were selected according to the standards. The tensile testswere performed for four numbers of each specimen. The mean of yield stresses in the specimenswere reduced after the repairing through half- thickness of the butt welds. Moreover, the mean ofyield stresses in the specimens after repairing would be decreased if the welding voltage andcurrent increased. Reduction of the hardness in heat affected zone and variation of the phases andgrain size after repairing were other outcomes from testing on the specimens.

The present research investigates improvement of Eddy Current (EC) technique as anondestructive method for measurement of ductile cast iron microstructural and mechanicalcharacteristics. Six samples of heat treated ductile cast iron have been selected to study therelations between pearlite content and EC outputs. These outputs include voltage and normalizedimpedance as well as calculated parameters of harmonic analysis. Furthermore, correlationbetween mechanical properties such as hardness, yield strength and ultimate tensile strength insamples containing different ferrite-pearlite matrices and the magnetic responses has also beenfound. High correlation coefficients of the relations indicate an acceptable level of accuracy incomparison with destructive method.